Rapid extraction of RNA from cells and tissues

ABSTRACT

A method of extracting RNA from biological systems (cells, cell fragments, organelles, tissues, organs, or organisms) is presented in which a solution containing RNA is contacted with a substrate to which RNA can bind. RNA is withdrawn from the substrate by applying negative pressure. No centrifugation step exceeds thirty seconds. Preferably, the RNA is diluted prior to filtration and one or more wash steps can be used to remove interferents. In one such method, except for DNA shearing and drying steps, centrifugation is not undertaken during the extraction step.

BACKGROUND

[0001] The invention relates to the extraction of RNA for use in, among other things, in vitro diagnostics.

[0002] As a result of recent progress in genomic technology and bioinformatics, new gene expression markers useful as diagnostic, prognostic and therapeutic indicators for cancer and other diseases are rapidly being discovered. To evaluate and apply these markers as in vitro diagnostic tests, there is a need for a rapid, sensitive, and easy-to-use method of RNA extraction from cells, tissues, and other biological components.

[0003] In oncology, rapid intra-operative molecular testing may be used to more sensitively detect surgical margins, lymph node or other sites of metastases, and to confirm the presence or absence of cancer in a tissue. To impact surgical care, diagnostic results useful in the intraoperative setting must be made available to the treating surgeon during the time that the patient is in the operating room, generally about 45 min. To allow time for reverse transcription and subsequent amplification and detection of molecular markers, amplifiable RNA from cells and tissues must be extracted and purified within a few minutes.

[0004] Several different approaches have been developed for the isolation and purification of RNA from cells and tissues. These include membrane-based methods, solution based methods, and magnetic based methods. Solution based methods generally require at least 90 minutes to perform and involve the use of toxic solvents. Magnetic particle methods have been developed but require at least 45 min to perform.

[0005] Kits for performing membrane based RNA purification are commercially available from several vendors. Generally, kits are-developed for the small-scale (30 mg or less) preparation of RNA from cells and tissues (eg. QIAGEN RNeasy Mini kit), for the medium scale (250 mg tissue) (eg. QIAGEN RNeasy Midi kit), and for the large scale (1 g maximum) (QIAGEN RNeasy Maxi kit). Unfortunately, currently available membrane based RNA extraction and purification systems require multiple steps, and may be too slow for intra-operative diagnostic applications.

[0006] Accordingly, a more rapid membrane-based RNA extraction method is needed particularly for use in intraoperative diagnostic applications.

SUMMARY OF THE INVENTION

[0007] The invention is a method of extracting RNA from biological systems (cells, cell fragments, organelles, tissues, organs, or organisms) in which a solution containing RNA is contacted with a substrate to which RNA can bind. RNA is withdrawn from the substrate by applying negative pressure. No centrifugation step exceeds thirty seconds. Preferably, the RNA is diluted prior to filtration and one or more wash steps can be used to remove interferents. In a further embodiment, except for DNA shearing and drying steps, centrifugation is not undertaken during the extraction step.

[0008] In a further aspect of the invention, cells without RNA of interest are removed from those with RNA of interest. The cells containing RNA of interest are then lysed and the lysate is contacted with a substrate containing or to which is affixed a material that binds (is adherent to) RNA. Negative pressure is applied to substrate for a period preferably less than 15 seconds and interferences are removed from the substrate without the application of centrifugation.

[0009] In a yet further aspect of the invention, a method of extracting RNA from biological systems has the following steps.

[0010] (a) obtaining a sample containing cells from the biological system,

[0011] (b) optionally, removing from the sample, cells without RNA of interest to produce a working sample,

[0012] (c) lysing the cells containing RNA that is of interest and producing a homogenate of them,

[0013] (d) diluting the homogenate,

[0014] (e) contacting the wetted, homogenized working sample with a substrate containing, or to which is affixed, a material to which RNA binds,

[0015] (f) allowing the sample to bind to the substrate,

[0016] (g) removing contaminants and interferents,

[0017] (h) drying the substrate, and

[0018] (i) eluting RNA from the substrate;

[0019] the method is conducted in less than 8 minutes.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The biological systems of the invention are organelles, cells, cell fragments, tissue, organs, or organisms. The solutions that contain RNA of interest can be obtained from any fluid found in or made from the biological system.

[0021] The successful isolation of intact RNA generally involves at least four steps: effective disruption of cells or tissue, denaturation of nucleoprotein complexes, inactivation of endogenous ribonuclease (RNAase) and removal of contaminating DNA and protein.

[0022] Depending on the sample containing the RNA of interest (i.e., the RNA whose marker(s) will be assayed) it may be desirable to remove cells without RNA of interest Removing cells without RNA of interest is preferably done by lysing them and removing the lysate from the solution. When working with whole blood, it is the red blood cells that make up the bulk of the cells present without RNA of interest since they are present in large quantities and are not nucleated. The red blood cells are very susceptible to hypotonic shock and can thus be made to burst in the presence of a hypotonic buffer. Lysing reagents are well known in the art and can include solutions containing ammonium chloride-potassium or ammonium oxalate among many others.

[0023] For tissues, commercial RNA extraction kits such as those offered by Qiagen, lysing buffers are used. Preferably, these contain a guanidine-thiocyante (GTC) solution and one or more surfactants such as sodium dodecylsulfate as well as a strong reducing agent such as 2-mercaptoethanol to inhibit or inactivate ribonucleases (RNAases). GTC has particularly useful disruptive and RNA protective properties. The GTC/surfactant combination acts to disrupt nucleoprotein complexes, allowing the RNA to be released into solution and isolated free of protein. Dilution of cell extracts in the presence of high concentrations of GTC causes selective precipitation of cellular proteins to occur while RNA remains in solution. Most preferably, RLT buffer (sometimes referred to as lysis or homogenization buffer) is used as it is commercially available from Qiagen and a component of their RNA extraction kits. Lysis and removal of cells and undesirable cellular components can be aided by mechanical disruption as with a homogenizer, bead mixer, mortor and pestle, hand grinder, or other similar device.

[0024] The distribution of metastases and micrometastases in tissues is not uniform in nodes or other tissues. Therefore, a sufficiently large sample should be obtained so that metastases will not be missed. One approach to sampling issue in the present method is to homogenize a large tissue sample, and subsequently perform a dilution of the well mixed homogenized sample to be used in subsequent molecular testing.

[0025] A dilution step after homogenization and prior to the addition of the homogenate to the RNA binding step (as described below) is particularly advantageous. The dilution step involves adding a diluent that is a reagent that dilutes the tissue homogenate without contributing to RNA instability. Preferably, it is a reagent such as the RLT buffer described above. Preferably, the homogenate is diluted at between 8 and 2 mg of homogenate per ml of diluent. More preferably, the homogenate is diluted at between about 4 and 2 mg /ml. Most preferably, the homogenate is diluted at about 4 mg/ml.

[0026] Such a dilution step allows for fast filtering, as for example, through a spin column. It also eliminates or greatly reduces clogging in spin columns, eliminates the need for subsequent large volumes of homogenization buffer, eliminates the need for subsequent centrifugation steps, and can eliminate the need for passage of the sample through a shredding column or device. Ultimately, such a dilution step renders RNA extraction easier and results in a more standardized protocol.

[0027] Cells, debris or non-RNA materials are generally removed through one or more wash steps, and the purified RNA is then extracted as, for example, by elution from a substrate-containing column.

[0028] The RNA is selectively precipitated out of solution with ethanol and bound to a membrane/substrate such as the silica surface of the glass fibers. The binding of RNA to the substrate occurs rapidly due to the disruption of the water molecules by the chaotropic salts, thus favoring absorption of nucleic acids to the silica. The bound total RNA is further purified from contaminating salts, proteins and cellular impurities by simple washing steps. Finally, the total RNA is eluted from the membrane by the addition of nuclease-free water.

[0029] Several kits for RNA extraction from tissues based on “spin column” purification have been commercialized. All are compatible with the method of this invention. These kits include those sold by Invitrogen Corp. (Carlsbad, Calif.), Stratagene (La Jolla, Calif.), BDBiosciences Clontech (Palo. Alto, Calif.), Sigma-Aldrich (St. Louis, Mo.), Ambion, Inc. (Austin, Tex.), and Promega Corp. (Madison, Wis.). Typically, these kits contain a lysis binding buffer having a guanidinium salt (4.0 M or greater) in buffer, wash solutions having different dilutions of ethanol in buffer either in the presence or absence of a chaotropic salt such as guanidinium, and an elution buffer, usually nuclease-free distilled water. Typically, contain reagents such as:

[0030] Lysis/Binding buffer (4.5 M guanidinium-HCl, 100 mM sodium phosphate),

[0031] Wash buffer I (37% ethanol in 5 M guanidine-HCL, 20 mM Tris-HCL),

[0032] Wash buffer II (80% ethanol in 20 mM NaCl, 2 mM Tris-HCl),

[0033] Elution buffer, and

[0034] Nuclease-free sterile double distilled water.

[0035] The use of a substrate to which RNA binds or to which a material is bound that RNA binds to is what distinguishes this method as a membrane-based RNA extraction method. RNA binds to such material by any chemical or physical means provided that the RNA is easily released by or from the material, as for example, by elution with a suitable reagent. Numerous substrates are now commonly used in membrane-based methods. Macherey-Nagel silica gel membrane technology is one such method and is described in EP 0496822 which is incorporated herein by reference. Essentially, RNA is adsorbed to a silica-gel membrane. High concentrations of chaotropic salts are included in the reagents which remove water from hydrated molecules in solution; polysaccharides and proteins do not adsorb and are removed. After a wash step pure RNA is eluted under low-salt conditions.

[0036] Ion exchange resins are also frequently used as substrates for RNA extraction in membrane-based systems. Qiagen, for example, has a commercially available anion exchange resin in which a low salt concentration is employed when the working sample is exposed to the substrate (binding), a high salt concentration is used during washing of the RNA, and precipitation is via an alcohol. The resin is silica-based with a high density of diethylaminoethyl groups (DEAE). Salt concentration and pH are controlled by the addition and use of the buffers for use with the substrate. An example of such an ion exchange resin available from Qiagen is as follows:

[0037] The most preferred substrate is a simple silica gel as follows:

[0038] In the presence of binding buffers, nucleic acids adsorb to the silica gel. In the preferred embodiments of this invention, the substrate is contained in a vessel such as a column. Most preferably, these columns are commercially obtained such as the “RNeasy” columns available from Qiagen, GbH.

[0039] The preferred method for extracting and purifying RNA from tissue samples less than 30 mg applying the reagents contained in the RNeasy Mini kit available from QIAGEN, GbH to the methods described herein. For extraction of larger amounts of RNA from larger tissue samples, the method described below can be readily scaled by. one of ordinary skill using, among other reagent configurations, kits commercially available as. QIAGEN RNeasy MIDI or QIAGEN RNeasy MAXI kits from QIAGEN, GbH.

[0040] When using such kits, the preferred method according to the instant invention is as follows:

[0041] For starting tissues of less than 20 mg, 350 to 600 ul of Homogenization Buffer (preferably, RLT buffer obtained in the kit from Qiagen) is added to the tissue, and for 20-30 mg of tissue, 600 ul of Buffer is preferably added. The amount of Homogenization buffer can be scaled depending upon the tissue sample. Tissue or cells are then disrupted by one of the following methods including but not limited to rotor-stator homogenizers, bead mixers, mortor and pestle, and by hand grinders. Homogenization is usually done by the use of a disposable tissue grinder (VWR Scientific, cat 15704-126 or 15704-124) when manual cell and tissue disruption is undertaken. More preferably, homogenization is conducted through the use of a mechanical device made for this purpose such as the PCR Tissue Homogenization Kit commercially available from Omni International (Warrenton, Va.).

[0042] Homogenization time is typically about one minute and preferably as soon as tissue is visibly homogenized.

[0043] It may be desirable, as with dense tissue samples, to decease the viscosity of the sample. Most preferably, this is done by the addition of homogenization buffer to homogenate (8 mg homogenate/ml buffer to 2 mg/ml). It can also be done with one or more passes through a needle (preferably about 20 guage) fitted to an RNAase-free syringe, or with a device such as a QIA shredder column used with centrifugation.

[0044] 1 volume of 70% ethanol is preferably added to the cleared lysate, and mixed by pipetting.

[0045] Up to about 700 ul of the sample prepared thus far is applied to a vessel housing the RNA binding matrix (preferably, an RNeasy silica gel mini column from the Qiagen kit) and/or discarded by filtration (as opposed to centrifugation) and preferably the application of vacuum. Preferably vacuum is applied at about 11 to 13 psi (as is the case for all vacuum steps) for about 15 to 60 sec. Here as in all steps in which vacuum is applied, the time in which it is applied can be decreased with an increase in vacuum pressure provided that it does not exceed the capacity of the matrix to withstand such pressure.

[0046] Wash Buffer (preferably about 700 μl of RW1 buffer from the Qiagen kit) is added to the vessel housing the RNA binding matrix (preferably, RNeasy column) and the flow-through fluid is removed/and or discarded by filtration preferably through filtration and preferably the application of vacuum and collection tube are then removed and/or discarded.

[0047] A second Wash Buffer (preferably about 500 ul of RPE buffer from the Qiagen kit) is pipetted on to the column. The tube is closed gently and the flow-through is removed and/or discarded by filtration and preferably the application of vacuum.

[0048] Optionally, wash buffer (preferably about 500 ul of RPE buffer) can be added again to the vessel (preferably, Rneasy column); The tube is gently closed and the substrate/membrane is dried. The vessel is preferably placed in a new 2 ml collection tube and centrifuged (preferably, for 1 minute at about 8,000 g).

[0049] For elution, the vessel is preferably transferred to a new 1.5 ml collection tube and 30-50 ul Rnase-free water is pipetted directly onto the substrate/membrane. The tube is closed gently and centrifuged (preferably at about 10,000 RPM for about 30 seconds) to elute the RNA. If the RNA yield is expected to exceed 30 ug, the steps of this paragraph are preferably repeated during elution.

[0050] The RNAeasy protocol for isolation of total RNA from animal tissue (QIAGEN RNAeasy Handbook, June 2001) requires total centrifuation times of at least 6 min 45 sec and 8 min 45 sec when acceleration and deceleration time for the centrifuge is included. In comparison, total time for all filtration and centrifugation steps in the rapid method of the instant invention is 2 min and 15 sec, and 3 min when acceleration and deceleration of the centrifuge are included. In addition about 30 sec to 1 min for tissue homogenization and about 45 sec to 1 min for sample manipulation (including dilution and mixing steps) are common to the method of the invention and the method of the prior art.

[0051] Thus, the total time for the method of this invention is less than eight minutes, preferably, less than six minutes. A total extraction time of five minutes is particularly desirable and attainable where the sample is a single lymph node.

[0052] A vacuum manifold such as a QIA vac 24 Vacuum Manifold is preferably used for convenient vacuum processing of spin columns in parallel. Samples and wash solutions are drawn through the column membranes by vacuum instead of centrifugation, providing greater speed, and reduced hands-on time in the extraction and purification of RNA from cells and tissues.

[0053] This method can be used to extract RNA from plant and animal cells as well as bacteria, yeast, plants, and filamentous fungi with an appropriate disruption method.

EXAMPLES Real-Time PCR

[0054] Examples in the present invention are based on the use of real-time PCR. In real-time PCR the products of the polymerase chain reaction are monitored in real-time during the exponential phase of PCR rather than by an end-point measurement. Hence, the quantification of DNA and RNA is much more precise and reproducible. Fluorescence values are recorded during every cycle and represent the amount of product amplified to that point in the amplification reaction. The more templates present at the beginning of the reaction, the fewer number of cycles it takes to reach a point in which the fluorescent signal is first recorded as statistically significant above background, which is the definition of the (Ct) values. The concept of the threshold cycle (Ct) allows for accurate and reproducible quantification using fluorescence based RT-PCR. Homogeneous detection of PCR products can be performed using many different detection methods including those based on double- stranded DNA binding dyes (e.g., SYBR Green), fluorogenic probes (e.g., Taq Man probes, Molecular Beacons), and direct labeled primers (e.g., Amplifluor primers).

Example 1. Short Centrifugation Time

[0055] In this example, two breast lymph nodes were purchased from Asterand Inc. (Detroit Mich.).

[0056] One node was confirmed as cancer positive by pathology (ALNC1) and a second node was negative for cancer (ALNN1).

[0057] As a control, 30 mg of tissue from each node was extracted and purified using the QIAGEN RNeasy Mini Procedure as recommended by the manufacturer and as described above. Triplicate extractions from a single homogenate were performed on each sample. In a similar manner, triplicate 30 mg sections were processed with the Qiagen RNeasy Mini Procedure, except that after the final addiiton of RPE wash buffer, each centrifugation step was reduced to 30 sec. All centrifugation steps were performed on an Eppendorf model 5415C microcentrifuge (Brinkman, Instruments, Inc, Westbury N.Y.).

[0058] The RNA extracted from each node was analyzed spectrophotometrically at 260 and 280 nm on a Hewlitt-Packard HP8453 UV-Visible Spectroscopy System (Waldbronn Germany), and the total RNA yield was determined at 260 nm and RNA quality was judged based on the 260 nm/280 nm ratio for each sample.

[0059] All reagents including primers were purchased from Invitrogen Corp, Carlsbad Calif. except where noted below.

[0060] The resulting RNA was transcribed to make cDNA copies as follows. A stock solution of 5 μL of anchored Oligo dT23, 5 μL of 10 mM each dNTP, and RNAase-treated water (Sigma Chemical Co, St. Louis, Mo.) to 50 μL was made, and 2.5 ug of RNA was added and the solution was heated to 70 C for 5 min, and then placed on ice. Then 38 μL of a solution of 20 μL of 5× Superscript First-Strand Buffer, 10 μL of 0.1M Dithiothreitol, 3 μL of a solution of 40 U/μL Rnasin (Promega Corp, Madison Wis.) and 5 μL of 200 U/μL Superscript II reverse transcriptase and RNAase free water (Sigma Chemical Co, St Louis, Mo.) to a volume of 38 μL was added. The tube was incubated at 42 C for 50 min, and then 40 μL of 0.5M NaOH was added and the tube was incubated at 70 C for 5 min. Twenty μL of 1M Tris-HCl buffer, pH 7.0, was added, followed by 90 ul of RNAase free water. Assuming complete conversion of RNA to cDNA, and a conversion factor of lug equal to 100,000 cell equivalents (CE), a concentration of 1000 CE/μL in 80 mM Tris buffer was used for all subsequent real-time PCR assays.

[0061] The following protocol based on SYBR green detection in a real-time PCR format was used for the quantitative detection of the housekeeping gene porphobilinogen deaminase (PBGD, Seq. ID No. 20), as well as for the breast cancer specific genes mammaglobin (Seq ID No. 17) and prolactin-inducibleprotein (PIP, Seq ID No. 18). A stock master mix solution of 10 μL of 10×PCR Buffer# 1 (Applied Biosystems, Inc, Foster City Calif.) , 0.1 μL of 10M MgCl₂, 2 μL of 10 mM of dNTP's, 1 μL of 100× SYBER Green solution (Sigma Chemical Co, St. Louis, Mo.), 2 μL of each primer from a 5 uM stock in TE buffer, and 0.75 μL of Taq/ anti-Taq antibody mix, and RNAase free water to 94 μL. The Taq DNA polymerase and anti-Taq antibodies were mixed and incubated for 10-15 minutes prior to the addition of the other reaction components. One μL of cDNA (1,000 CE) was added to each well along with 49 ul of the above master mix solution.

[0062] The following primer pairs were used: For PBGD, SEQ ID NO. 1 and SEQ ID NO. 2; for mammaglobin, SEQ ID NO. 3 and SEQ ID NO. 4; and for PIP, SEQ ID NO. 5 and SEQ ID NO. 6. SEQ ID NO. 1 ATGACTGCCT TGCCTCCTCA GTA (PBGD) SEQ ID NO. 2 GGCTGTTGCT TGGACTTCTC TAAAGA (PBGD) SEQ ID NO. 3 CAAACGGATG AAACTCTGAG CAATGTTGA (MAMAGLOBIN) SEQ ID NO. 4 TCTGTGAGCC AAAGGTCTTG CAGA (MAMAGLOBIN) SEQ ID NO. 5 GGCCAACAAA GCTCAGGACA ACA (PIP) SEQ ID NO. 6 GCAGTGACTT CGTCATTTGG ACGTA (PIP)

[0063] Real-time PCR measurements were performed on an Applied Biosystems 7900 (Foster City Calif.). A thermal profile of 94 C for 2 min , followed by 50 cycles of 94 C for 15 sec, 62 C for 15 sec. and 72 C for 45 sec was used, as well as a threshold value of 275.

[0064] Results of these experiments are summarized in Table 1 and indicate no large differences in either RNA yield or amplification efficiency of the housekeeping gene, PBGD or the cancer genes mammaglobin and PIP between the samples extracted with shortened centrifugation steps as compared to the standard QIAGEN procedure. These results indicate that the rapid centrifugation protocol does not inhibit the reverse-transcription or PCR steps. TABLE 1 Effect of Reduced Centrifugation Time on RNA yield and Real-time PCR in Breast lymph nodes. Total Yield Method of Ct Values Sample 260 280 Ratio ng/μl (μg) Extraction PBGD MG PIP ALNC1.1 1.33 0.67 2.0 266 13.3 Prior Art 25.69 20.84 25.57 ALNC1.2 1.11 0.57 1.9 222 11.1 Prior Art 23.77 19.19 24.76 ALNC1.3 1.18 0.62 1.9 236 11.8 Prior Art 23.57 18.25 24.80 ALNN2.1 0.97 0.482 2.0 195 9.7 Prior Art 26.24 23.37 26.63 ALNN2.2 1.63 0.802 2.0 326 16.3 Prior Art 23.42 20.51 25.19 ALNN2.3 1.61 0.799 2.0 322 16.1 Prior Art 26.01 22.14 24.84 ALNC1.4 1.45 0.72 2.0 290 14.5 30 sec 25.60 18.49 24.10 centrifugation ALNC1.5 1.15 0.59 2.0 230 11.5 30 sec 25.44 20.07 25.80 centrifugation ALNC1.6 1.55 0.8 1.9 310 15.5 30 sec 24.35 19.36 25.92 centrifugation ALNN2.4 1.54 0.781 2.0 308 15.4 30 sec 25.15 23.96 27.02 centrifugation ALNN2.5 1.38 0.692 2.0 280 14.0 30 sec 23.90 20.57 25.46 centrifugation ALNN2.6 1.5 0.749 2.0 300 15.0 30 sec 23.60 20.35 25.98 centrifugation

[0065] As additional evidence for good RNA quality in the rapid protocol, RNA quality for all the above samples was also evaluated by means of an Agilent 2100Bioanalyzer using the 6000 Nano-chip Kit (Agilent Technologies, Wilmington Del.). Electropherogram results indicated comparable good quality RNA based on the presence of well-defined 18 s and 28 s ribosomal peaks with minimal RNA degradation. All samples had a ribosomal peak ratio near 1.6 or greater, based on the Agilent Bioanalyzer data, also confirming high quality RNA from the shortened centrifugation protocol. The total time for RNA extraction was 5 min 15 sec.

Example 2 RNA Yield, Reverse Transcription, and Real-Time PCR Amplification

[0066] In this experiment, a breast axillary node with ductal carcinoma was-used. All reagents were from the QIAGEN RNeasy Kit (cat 74181, QIAGEN, Inc. Valencia Corporation). The following supplies and equipment also were purchased from QIAGEN INC: QIAvac 24 filtering apparatus (cat 19403), QIAshredder (cat 79656), QIAvac connectors (cat 19409), and VacConnectors (cat 19407). All other reagents were obtained from sources as described in Example 1.

[0067] For this experiment tissue homogenization, 540 mg of breast node tissue was suspened in 10.8 ml of Buffer RLT and homogenized prior to use. The resultant homogenate was treated in several different ways.

[0068] Part I. Evaluation of Vacuum Manifold. This experiment was performed using a QIAvac 24 filtering apparatus with an applied vacuum.

[0069] 1. 700 μL of homogenate were placed into a QIAshredder colum and centrifuged at 14,000 RPM for 2 min.

[0070] 2. An equal volume of 70% ethanol was added to the lysate and mixed by pipetting.

[0071] The next step was continued without delay

[0072] 3. 700 μL of sample was applied to an, RNEasy mini column attached to a vacuum manifold. Vacuum was applied at 12 psi for 10 sec.

[0073] 4. 700 μL of Buffer RWI were applied to the column, and the same vacuum pressure was applied for the same duration.

[0074] 5. 500 μL of Buffer RPE were pipetted onto the column and the same vacuum pressure was applied for the same duration. Another 500 μL of Buffer RPE was added to the column and the same vacuum pressure applied for the same duration.

[0075] 6. The column was placed into a collection tub and centrifuged at 14,000 rpm for 1 min to dry the column.

[0076] 7. The column was transferred to a new 1.5 ml tube. Pipet 25 μL of RNAse-free water directly onto the membrane.

[0077] 8. The membrane was centrifuged for 60 sec to elute.

[0078] Part II was performed to determine the effect of reducing the centifugation time to 30 sec as well as the use of a vacuum manifold

[0079] 1. 700 μL of homogenate were placed into a QIAshredder colum and centrifuged at 14,000 RPM for 30 sec.

[0080] 2. An equal volume of 70% ethanol was added to the lysate and mixed by pipetting. The next step was continued without delay

[0081] 3. 700 μL of sample was applied to an RNEasy mini column attached to a vacuum manifold. Vacuum was applied at 12 psi for 10 sec.

[0082] 4. 700 μL of Buffer RWI was applied to the column, and vacuum applied as above.

[0083] 5. 500 μL of Buffer RPE were pipetted onto the column and vacuum applied as above. Another 500 μL of Buffer RPE were applied to the column and vacuum applied as above.

[0084] 6. The column was placed into a collection tube and centrifuged at 14,000 rpm for 30 sec to dry the column.

[0085] 7. The column was transferd to a new 1.5 ml tube. 25 μL of RNAse-free water was pipetted directly onto the membrane.

[0086] 8. Centrifugation was conducted for 30 sec to elute.

[0087] Part III. Use of lower speed centrifuge.

[0088] In this experiment, a model 10MVSS centrifuge, purchased from VWR Scientific, West Chester, Pa. was used in steps 1, 6 and 7 of Part II above at 10,000 rpm.

[0089] Part IV. Eliminate Column Drying Step.

[0090] As a negative control, an experiment was included in which step 6 (Part II) was eliminated from the procedure described in Part II.

[0091] RNA yield in each of these parts, 260/280 nm ratio of the RNA (an estimate of RNA purity), and real-time PCR assays based on SYBR Green for the housekeeping gene PBGD with 3′ and 5′ primers are shown in Table 2 below. Procedures and reagents are as described in Example 1. TABLE 2 RNA extraction from a breast node. Total RNA PBGD 3′ GCLNC-7 Protocol Yield RNA Ct PBGD 5′ Sample Description (μg) Ratio (260/280) Ct MG Ct 1 Kit Manufacturer's 31.82 2.1 27.43 28.35 23.26 Protocol (control) 2A Centrifugation time 30.35 2.1 27.55 28.4 23.2 reduced 2B Eliminated 1 RPE 28.11 2.1 27.35 28.27 23.09 Wash 2C Used VWR mini- 27.91 2.1 27.14 28.51 22.98 microfuge 2D Eliminated column 15.17 2.1 27.36 49.69 23.01 drying step 2-1 Modifications 1-2C 23.5 2.1 27.42 29.77 23.56 made (all) BBC-2 positive N/A N/A N/A 30.18 28.36 17.6 control NTC negative N/A N/A N/A 49.03 50 41.71 control

[0092] Results of these experiments indicate that protocol which increase speed and lower instrument costs resulted in some loss of yield of RNA. However, the amount of RNA yielded by the modified protocol is well above that which is required for a reverse transcriptase reaction (2 to 2.5 μg). Real-time PCR results confirm that this rapid protocol results in RNA that can be transcribed and quantified by real-time PCR.

Example 3 Rapid v. Prior Art Protocols (Based on Real-Time PCR with Taqman Assays)

[0093] A total of 16 H&E positive nodes and 15 H&E negative breast node samples were purchased from Genomics Collaborative. Two 30 mg pieces of tissue were cut from each node.

[0094] Part I. One 30 mg piece of tissue was processed as follows: 600 ul of Buffer RLT was added and the tissue sample was homogenized manually for 20-40 sec by means of a disposable tissue grinder (cat 15704-126, VWR Scientific, West Chester, Pa.). The tube was centrifuged for 3 min at maximum speed in Eppendorf model 5415 C microcentrifuge. The supernatant fluid was transferred to a new tube, and 1 volume of 70% ethanol was added.

[0095] Sample (700 μL) was applied to an RNeasy mini column placed on the QIAvac 24 vacuum manifold and the vacuum was applied. Buffer RWI (700 μL) and allowed to filter through the column. Buffer RPE (500 μL) was pipetted onto the column and allowed to filter through. Another 500 μL of Buffer RPE was added to the column, and allowed to filter through. The RNeasy column was placed in a 2 ml collection tube and centrifuged in a microfuge at maximum speed for 1 min. The RNA was then eluted from the column, by transfering the RNeasy colum to a new 1.5 ml collection tube, adding 50 ul of RNAase-free water, and centrifuging for 1 min at 8000×g.

[0096] Part II. The second 30 mg piece of breast node tissue was processed by a rapid protocol as follows: (l)The tissue piece was added to 600 μL of Buffer RLT and homogenized manually for 20-40 sec by means of a disposable tissue grinder. (2) The homogenate was centrifuged through a QIAshredder column for 30 sec at maximum speed. (3) 1 volume of 70% ethanol was added to the lysate and mixed by pipetting. (4) The sample was then applied to an RNeasy mini column placed on the QIAvac 24 vacuum manifold and a vacuum was applied. (5) 700 ul of Buffer RWI was added to the column, and allowed to filter through the column. (6) 500 ul of Buffer RPE was added onto the column and allowed to filter through. (7) The column was transferred to a 2 ml collection tube, and centrifuged for 30 sec at 10,000 rpm. (8) 25 μL of RNAase-free water was added to the membrane and the column was centrifuged for 30 sec at 10,000 rpm to elute the RNA. All centrifugation steps in the rapid protocol were performed on a model 10MVSS VWR centrifuge.

[0097] Extracted RNA was reverse transcribed, and RNA and cDNA were quantified as described previously in Example 1.

[0098] For Taqman assays, Taqman Core Reagent Kit, Gene Amp 101×PCR Buffer 1, Amp Erase Uracil N-glycosidase, and AmpliTaq Gold DNA Polymerase were purchased from Applied Biosystems, Foster City, Calif. All other reagents were from commercial sources described in example 1. Glycerol was purchased from Sigma Chemical Co (St. Louis, Mo.) and Tween 20 from Eastman Organic Chemicals (Rochester, N.Y.)

[0099] Mammaglobin primers (SEQ ID NO. 3 and SEQ ID NO. 4) were synthesized by Invitrogen Corp.(Carlsbad, Calif.). and the mammaglobin Taqman probe (SEQ ID NO. 7) from Epoch Biosciences (San Diego, Calif.). PBGD primers (SEQ ID NO 8 and SEQ ID NO. 9) were synthesized by QIAGEN Operon (Alameda, Calif.), and the probe (SEQ ID NO. 23) by SYNTHEGEN, LLC (Houston, Tex.). B305D primers (SEQ ID NO. 11 and SEQ ID NO. 12) were synthesized at Invitrogen Corp and the probe (SEQ ID NO. 13) by

[0100] Applied Biosystems, Inc. For all Taqman probes, carboxyfluorescein (FAM) and carboxytetramethylrhodamine TAMRA) were used as the dye and quencher pair. SEQ ID NO. 3 CAAACGGATG AAACTCTGAG CAATGTTGA SEQ ID NO. 4 TCTGTGAGCC AAAGG TCTTG CAGA SEQ ID NO. 7 6-FAM - TGTTTATGCA ATTAATATAT GACAGCAGTC TTTGTG- TAMRA SEQ ID NO. 8 CTGAGGCACC TGGAAGGAGG SEQ ID NO. 9 CATCTTCATG CTGGGCAGGG SEQ ID NO. 23 6- FAM-CCTGAGGCAC CTGGAAGGAG GCTGCAG TGT- TAMRA SEQ ID NO. 11. TCTGATAAAG GCCGTACAAT G SEQ ID NO. 12 TCACGACTTG CTGTTTTTGC TC SEQ ID NO. 13 6-FAM-ATCAAAAAACA AGCATGGCCTA CACC- TAMRA

[0101] For the Taqman assays, a master mix was prepared by adding 10 μL of 10× PCR Buffer#1, 14 μL of 25 mM MgCl₂, 8 μL of 10 mM dNTP's, 1 μL of AmpErase UNG (1 U/μL), 16 μL of gycerol, 1 μL of 1% w/v Tween 20, 0.75 μL of AmpliTaq Gold (5 U/μL), 6 μL of each primer from a 5 μM stock, 0.4 μL of a 10 μM stock of probe, and water to a final volume of 96 μL. Master mix (48 μL) and 2 μL of cDNA from each node sample were added to each optical reaction microtiter plate well. After capping with optical caps, the plates were processed in an ABI Prism 7900 HT Sequence Detection System (Applied Biosystems, Inc., Foster City, Calif.). Commercial reagents including Taqman PCR Core Reagent Kit, Taqman DNA Template Reagents, and Taqman B-actin Dectection Reagents were purchased from Applied Biosystems (Foster City, Calif.) and the assay was performed according to the protocol recommended by the manufacturer. A threshold value of 0.02 was used for analysis with the mammaglobin assay, 0.03 for the B305D assay, 0.08 for the B-actin assay, and 0.1 for the PBGD assay. The average of triplicate determination by Taqman assays are shown in Tables 3 and 4.

[0102] A comparison of the real-time measurement of the housekeeping genes B-actin (SEQ ID NO. 19) and PBGD are shown in Table 3 in 15 H&E negative node samples as well as 16 H&E positive nodes and two control cDNA samples are shown in Table 3. Results of these experiments indicate good agreement between Ct values obtained with the rapid method of this invention and prior art protocol confirming that RNA extracted by the rapid RNA extraction protocol is capable of being reverse transcribed and PCR amplified to a similar extent as RNA extracted based on the prior art protocol.

[0103] Table 4 compares gene expression results based on Ct value for the breast cancer markers mammaglobin and B305D (isoform C, SEQ ID NO. 14) with the same breast node samples evaluated in Table 3. To determine whether a correlation can be made between H&E positive and H&E negative breast node samples based on real-time PCR results, the lowest Ct value for each marker in the H&E negative node samples was identified for both mammaglobin and B305D. An arbitrary, but conservative, cut-off of 2.5Ct values less than this lowest value among H&E negative samples was applied to the H&E positive samples. Samples that are shaded in the Table 4 have higher expression for these two breast markers, in that Ct value is at least 2.5Ct values lower than a Ct value observed among H&E negative samples. There was a good correlation in expression of these markers using both the rapid method of this invention and the prior art method as recommended by the manufacturer of the kit, QIAGEN .

[0104] Using mammaglobin as a marker in one of 15 H&E negative nodes samples, GCLNC-24 exhibited difference in Ct value of 0.4 which is within experimental error. The second sample showed a larger difference in Ct. larger differences in Ct value with both mammaglobin and B305D may be due to difficulties in spectrally quantifying RNA in these samples as well as to possible sampling problems due to the well established non-uniform distribution of metastases in nodes. (Cserni. 1999. Metastases in axillary sentinel lymph nodes in breast cancer as detected by intensive histopathological work up. J. Clin Pathol, 52:0922-924). TABLE 3 Comparison of RNA extracted by the rapid method and Prior Art Method as measured by Taqman Assays for the Housekeeping Genes B-actin and PBDG B-Actin PBGD Ct Values Ct Values Sample Template Qiagen Rapid Qiagen Rapid H&E Negative 1 GCLNN-10 20.7 21.9 32.6 34.1 2 GCLNN-11 20.5 21.0 33.7 32.7 3 GCLNN-12 21.7 22.5 32.8 32.8 4 GCLNN-14 21.2 19.1 32.1 31.0 5 GCLNN-15 19.8 21.3 32.5 39.9 6 GCLNN-19 22.4 23.0 29.9 39.1 7 GCLNN-20 17.8 18.6 31.7 30.9 8 GCLNN-23 21.4 19.2 33.1 31.4 9 GCLNN-24 21.1 26.1 36.9 37.0 10 GCLNN-25 19.1 21.4 32.7 33.1 11 GCLNN-26 23.8 26.7 40.0 39.7 12 CBLNN-274 20.1 19.8 31.5 30.7 13 CBLNN-257 20.4 22.6 32.8 34.0 14 CBLNN-258 23.4 27.6 33.1 35.4 15 CBLNN-262 23.0 23.6 33.0 32.1 H&E Positive 16 GCLNC-1 18.7 18.5 28.8 29.1 17 GCLNC-5 20.4 21.6 31.3 31.0 18 GCLNC-6 20.0 19.9 31.4 30.2 19 GCLNC-7 20.6 28.2 29.3 32.1 20 GCLNC-11 18.9 19.5 31.2 30.9 21 GCLNC-12 26.1 23.8 32.6 31.2 22 GCLNC-13 20.5 18.9 30.8 27.7 23 GCLNC-16 20.5 22.7 31.1 30.5 24 GCLNC-17 22.1 19.4 40.0 29.1 25 GCLNC-20 20.0 19.5 31.9 29.6 26 GCLNC-21 21.1 21.3 33.5 32.2 27 GCLNC-22 24.2 22.9 29.3 32.1 28 GCLNC-23 18.4 20.7 29.6 35.5 29 GCLNC-24 19.1 19.5 29.4 30.1 31 ALNC-1 21.1 19.4 30.2 30.8 32 ALNN-2 18.9 19.5 31.4 30.0 33 CBLNN-247 18.2 20.7 31.5 31.1

[0105] TABLE 4 Comparison of RNA extracted by the rapid method and by the Prior Art Method as measured by Taqman Assays for the Cancer Genes Mammaglobin and B305D

Example 4 Evaluation of a QIAshredder Column

[0106] It is the purpose of this example to demonstrate that the QIAshredder column can be used after homogenization of lymph node tissue, and that centrifugation of the homogenate for only 30 seconds yields acceptable RNA extraction. A breast axillary node that was H&E—negative was obtained from Genomics Collaborative (Cambridge, Mass.). A 490 mg slice of tissue was mixed with 5.5 ml of Buffer RLT, and the node was homogenized. Six hundred microliters of homogenate was removed and RNA was extracted using all the protocol shortening modifications as described in Example 2. As a control, another 600 μL of homogenate was treated using all the protocol shortening modifications as described in Example 2, except that a 3 min centrifugation was used instead of the QIAshredder column. The RNA from each reaction was reverse transcribed and quantified as described in Example 1. Real-time PCR was performed using Taqman probes as described previously in Example 3.

[0107] Results of these studies indicated similar RNA yields of 0.31 μg/μL in the protocol involving the QIAshredder protocol as compared to 0.34 μg/μL in the centrifugation protocol. Identical 260/280 nm ratio's of 2.1 were obtained in both samples indicating high quality RNA. Real-time PCR assays also indicated similar Ct values for Mammaglobin with RNA extracted by the QIAshredder column as compared to the protocol involving (22.5 versus 22.0), as well as with B305D (26.7 versus 26.6) as well as with the housekeeping genes PBGD (29.1 versus 29.0), and B-actin (18.5 versus 18.2).

[0108] In summary, this experiment indicates similar RNA yield, quality and real-time PCR amplfication results with the protocol involving a QIAshredder substituted for a 3 min centrifugation step after homogenization. This modification reduces the time required to perform RNA extraction by 2.5 minutes, which is important in developing protocols suitable for intraoperative and other applications in which fast results are required to impact patient care.

Example 5 Comparison of Rapid RNA Extraction Method and Standard (Prior Art) QIAGEN Protocol on Colon Tissue

[0109] The following example compares the extraction of RNA from colon tissue with both the method of the invention and the prior art. Twenty mg of colon tissue was added to 600 ul of Buffer RLT and homogenized as described in Example 3. One sample of homogenizaed colon cancer tissue was treated according to the rapid procol as described in Example 3A and one sample was treated according to the QIAGEN protocol as described in Example 3, part B. Resultant RNA from both procedures was tested on the Agilent Bioanalyzer.

[0110] Electropherograms for RNA extracted with the rapid method and the prior art showed that the RNA ratio of sample processed with the QIAGEN protocol was 1.54 and the sample treated with the rapid protocol was 1.37. Generally, any sample with an RNA ratio above 1.1 is considered acceptable. As determined by the Agilent Bioanalyzer, the sample processed with rapid protocol had an RNA yield of 1 36 ug/ml, whereas the sample treated with the QIAGEN method had a yield of 280 ug/ml. The yield obtained by both protocol is well above that which is required for a reverse transcriptase reaction (2 to 2.5 ug).

Example 6 Effect of Diluting of Lysate on RNA Yield and Precision

[0111] The following example illustrates the effect of dilution of the lysate on RNA yield and precision of RNA recovery. In this example, 20 mg, 10 mg or 5 mg of frozen pig node tissue was cut. Tissue was ground using a 50 ml Disposable Tissue Grinder for 30 sec, and the samples were vortexed. Three replicates were performed for each node weight. One ml of each lysate was transferred to a 1.7 ml microcentrifuge tube which was then centrifuged in an Eppendorf microfuge at maximum speed (14,000 RPM) for 30 sec. Seven hundred microliters was centrifuged through a QIAshredder column and the samples were centrifuged at maximum speed for 30 sec. The column was then washed, the column dried, and RNA eluted as described previously in Example 2, Part I steps 4-8. RNA was quantified by means of a Gene Spec II. Results of these studies are shown in Table 5, and illustrates excellent precision at an initial node tissue weight of 2.5 mg homogenized in 600 ml of homogenization buffer, as compared to samples with higher weights including 10 mg and 20 mg node tissue. These results indicate that improved precision of RNA recovery can be obtained at lower node weight. Also, it would be expected that more dilute homogenates would be filtered faster through the column, and that there would be even fewer potential problems with filter clogging.

Example 7

[0112] The following example was performed to demonstrate that with dilution of the homogenate, there is no need for a centrifugation step after homogenization, and that processing through a device such as a QIAshredder is not necessary to rapidly extract RNA.

[0113] In this example, each 200 mg piece of pig lymph node tissue was suspended in 4 ml of homogenization Buffer RLT and homogenized in a disposable 50 ml Tissue Grinder for 30 sec. An additional 20 ml of Buffer RLT was added so that the final concentration of tissue was 5 mg in 600 ml of buffer. The sample was vortexed for 15 sec and the tissue concentration was diluted to either 2.5 mg, 1.25 mg, or 0.625 mg in 600 ml of Buffer RLT. Triplicate determinations for the following variables were performed:

[0114] (1) centrifugation after homogenization and QIAshredder step, (II) centrifugation, no QIAshredder step, (III)QIAshredder, no centrifugation step, and (IV), no QIAshredder, no centrifugation of the homogenate after tissue homogenization. Each sample was diluted with an equal volume of 70% ethanol, and mixed. The sample (700 ul) was applied to a RNEasay mini column, and placed on a QIAGEN vacuum manifold. The sample was filtered by vacuum, and the column washed with 700 ul of Buffer RWI Buffer, followed by 500 ul of Buffer RPE. The column was added to a new collection tube and centrifuged at full speed (14,000 RPM) for 30 sec to dry the column. Each column then was transferred to a new collection tube, and 50 ul of RNAase-free water was pipetted onto the membrane, and the tube was centrifuged for 30 sec at 14,000 ×g to elute the RNA. RNA yield was quantified spectrophotometrically. Results of these studies are summarized below in Table 5, and indicate that at the samples with lower weight of tissue (2.5 mg, 1.25 mg, and 0.625 mg), no improvement is seen when either the QIAshredder, or a centrifugation step after homogenization, or both are included in the assay.

1 35 1 27 DNA Artificial Artificial Sequence is a Primer 1 tcccatcaga atccaaacaa gaggaag 27 2 26 DNA Artificial artifiical sequence is a primer 2 ggctgttgct tggacttctc taaaga 26 3 29 DNA Artificial Artificial sequence is a primer 3 caaacggatg aaactctgag caatgttga 29 4 24 DNA Artificial Artficial sequence is a primer 4 tctgtgagcc aaaggtcttg caga 24 5 23 DNA Artificial Artificial sequence is a primer 5 ggccaacaaa gctcaggaca aca 23 6 25 DNA Artificial Artificial sequence is a Primer 6 gcagtgactt cgtcatttgg acgta 25 7 36 DNA Artificial Artificial sequence is a Probe 7 tgtttatgca attaatatat gacagcagtc tttgtg 36 8 20 DNA Artificial Artificial sequence is a Primer 8 ctgaggcacc tggaaggagg 20 9 20 DNA Artificial Artificial sequence is a Primer 9 catcttcatg ctgggcaggg 20 10 29 DNA Artificial Artificial sequence is a Primer 10 ctgaggcacc tggaaggagg ctgcagtgt 29 11 21 DNA Artificial Artificial sequence is a Primer 11 tctgataaag gccgtacaat g 21 12 22 DNA Artificial Artificial sequence is a Primer 12 tcacgacttg ctgtttttgc tc 22 13 26 DNA Artificial Artificial sequence is a Probe 13 atcaaaaaac aagcatggcc tacacc 26 14 1155 DNA Human 14 atggtggttg aggttgattc catgccggct gcctcttctg tgaagaagcc atttggtctc 60 aggagcaaga tgggcaagtg gtgctgccgt tgcttcccct gctgcaggga gagcggcaag 120 agcaacgtgg gcacttctgg agaccacgac gactctgcta tgaagacact caggagcaag 180 atgggcaagt ggtgccgcca ctgcttcccc tgctgcaggg ggagtggcaa gagcaacgtg 240 ggcgcttctg gagaccacga cgactctgct atgaagacac tcaggaacaa gatgggcaag 300 tggtgctgcc actgcttccc ctgctgcagg gggagcagca agagcaaggt gggcgcttgg 360 ggagactacg atgacagtgc cttcatggag cccaggtacc acgtccgtgg agaagatctg 420 gacaagctcc acagagctgc ctggtggggt aaagtcccca gaaaggatct catcgtcatg 480 ctcagggaca ctgacgtgaa caagcaggac aagcaaaaga ggactgctct acatctggcc 540 tctgccaatg ggaattcaga agtagtaaaa ctcctgctgg acagacgatg tcaacttaat 600 gtccttgaca acaaaaagag gacagctctg ataaaggccg tacaatgcca ggaagatgaa 660 tgtgcgttaa tgttgctgga acatggcact gatccaaata ttccagatga gtatggaaat 720 accactctgc actacgctat ctataatgaa gataaattaa tggccaaagc actgctctta 780 tatggtgctg atatcgaatc aaaaaacaag catggcctca caccactgtt acttggtgta 840 catgagcaaa aacagcaagt cgtgaaattt ttaattaaga aaaaagcgaa tttaaatgca 900 ctggatagat atggaaggac tgctctcata cttgctgtat gttgtggatc agcaagtata 960 gtcagccttc tacttgagca aaatattgat gtatcttctc aagatctatc tggacagacg 1020 gccagagagt atgctgtttc tagtcatcat catgtaattt gccagttact ttctgactac 1080 aaagaaaaac agatgctaaa aatctcttct gaaaacagca atccagaaaa tgtctcaaga 1140 accagaaata aataa 1155 15 3865 DNA Human 15 tccgagctga ttacagacac caaggaagat gctgtaaaga gtcagcagcc acagccctgg 60 ctagctggcc ctgtgggcat ttattagtaa agttttaatg acaaaagctt tgagtcaaca 120 cacccgtggg taattaacct ggtcatcccc accctggaga gccatcctgc ccatgggtga 180 tcaaagaagg aacatctgca ggaacacctg atgaggctgc acccttggcg gaaagaacac 240 ctgacacagc tgaaagcttg gtggaaaaaa cacctgatga ggctgcaccc ttggtggaaa 300 gaacacctga cacggctgaa agcttggtgg aaaaaacacc tgatgaggct gcatccttgg 360 tggagggaac atctgacaaa attcaatgtt tggagaaagc gacatctgga aagttcgaac 420 agtcagcaga agaaacacct agggaaatta cgagtcctgc aaaagaaaca tctgagaaat 480 ttacgtggcc agcaaaagga agacctagga agatcgcatg ggagaaaaaa gaagacacac 540 ctagggaaat tatgagtccc gcaaaagaaa catctgagaa atttacgtgg gcagcaaaag 600 gaagacctag gaagatcgca tgggagaaaa aagaaacacc tgtaaagact ggatgcgtgg 660 caagagtaac atctaataaa actaaagttt tggaaaaagg aagatctaag atgattgcat 720 gtcctacaaa agaatcatct acaaaagcaa gtgccaatga tcagaggttc ccatcagaat 780 ccaaacaaga ggaagatgaa gaatattctt gtgattctcg gagtctcttt gagagttctg 840 caaagattca agtgtgtata cctgagtcta tatatcaaaa agtaatggag ataaatagag 900 aagtagaaga gcctcctaag aagccatctg ccttcaagcc tgccattgaa atgcaaaact 960 ctgttccaaa taaagccttt gaattgaaga atgaacaaac attgagagca gatccgatgt 1020 tcccaccaga atccaaacaa aaggactatg aagaaaattc ttgggattct gagagtctct 1080 gtgagactgt ttcacagaag gatgtgtgtt tacccaaggc tacacatcaa aaagaaatag 1140 ataaaataaa tggaaaatta gaagagtctc ctaataaaga tggtcttctg aaggctacct 1200 gcggaatgaa agtttctatt ccaactaaag ccttagaatt gaaggacatg caaactttca 1260 aagcagagcc tccggggaag ccatctgcct tcgagcctgc cactgaaatg caaaagtctg 1320 tcccaaataa agccttggaa ttgaaaaatg aacaaacatt gagagcagat gagatactcc 1380 catcagaatc caaacaaaag gactatgaag aaagttcttg ggattctgag agtctctgtg 1440 agactgtttc acagaaggat gtgtgtttac ccaaggctrc rcatcaaaaa gaaatagata 1500 aaataaatgg aaaattagaa gggtctcctg ttaaagatgg tcttctgaag gctaactgcg 1560 gaatgaaagt ttctattcca actaaagcct tagaattgat ggacatgcaa actttcaaag 1620 cagagcctcc cgagaagcca tctgccttcg agcctgccat tgaaatgcaa aagtctgttc 1680 caaataaagc cttggaattg aagaatgaac aaacattgag agcagatgag atactcccat 1740 cagaatccaa acaaaaggac tatgaagaaa gttcttggga ttctgagagt ctctgtgaga 1800 ctgtttcaca gaaggatgtg tgtttaccca aggctrcrca tcaaaaagaa atagataaaa 1860 taaatggaaa attagaagag tctcctgata atgatggttt tctgaaggct ccctgcagaa 1920 tgaaagtttc tattccaact aaagccttag aattgatgga catgcaaact ttcaaagcag 1980 agcctcccga gaagccatct gccttcgagc ctgccattga aatgcaaaag tctgttccaa 2040 ataaagcctt ggaattgaag aatgaacaaa cattgagagc agatcagatg ttcccttcag 2100 aatcaaaaca aaagaasgtt gaagaaaatt cttgggattc tgagagtctc cgtgagactg 2160 tttcacagaa ggatgtgtgt gtacccaagg ctacacatca aaaagaaatg gataaaataa 2220 gtggaaaatt agaagattca actagcctat caaaaatctt ggatacagtt cattcttgtg 2280 aaagagcaag ggaacttcaa aaagatcact gtgaacaacg tacaggaaaa atggaacaaa 2340 tgaaaaagaa gttttgtgta ctgaaaaaga aactgtcaga agcaaaagaa ataaaatcac 2400 agttagagaa ccaaaaagtt aaatgggaac aagagctctg cagtgtgaga ttgactttaa 2460 accaagaaga agagaagaga agaaatgccg atatattaaa tgaaaaaatt agggaagaat 2520 taggaagaat cgaagagcag cataggaaag agttagaagt gaaacaacaa cttgaacagg 2580 ctctcagaat acaagatata gaattgaaga gtgtagaaag taatttgaat caggtttctc 2640 acactcatga aaatgaaaat tatctcttac atgaaaattg catgttgaaa aaggaaattg 2700 ccatgctaaa actggaaata gccacactga aacaccaata ccaggaaaag gaaaataaat 2760 actttgagga cattaagatt ttaaaagaaa agaatgctga acttcagatg accctaaaac 2820 tgaaagagga atcattaact aaaagggcat ctcaatatag tgggcagctt aaagttctga 2880 tagctgagaa cacaatgctc acttctaaat tgaaggaaaa acaagacaaa gaaatactag 2940 aggcagaaat tgaatcacac catcctagac tggcttctgc tgtacaagac catgatcaaa 3000 ttgtgacatc aagaaaaagt caagaacctg ctttccacat tgcaggagat gcttgtttgc 3060 aaagaaaaat gaatgttgat gtgagtagta cgatatataa caatgaggtg ctccatcaac 3120 cactttctga agctcaaagg aaatccaaaa gcctaaaaat taatctcaat tatgcmggag 3180 atgctctaag agaaaataca ttggtttcag aacatgcaca aagagaccaa cgtgaaacac 3240 agtgtcaaat gaaggaagct gaacacatgt atcaaaacga acaagataat gtgaacaaac 3300 acactgaaca gcaggagtct ctagatcaga aattatttca actacaaagc aaaaatatgt 3360 ggcttcaaca gcaattagtt catgcacata agaaagctga caacaaaagc aagataacaa 3420 ttgatattca ttttcttgag aggaaaatgc aacatcatct cctaaaagag aaaaatgagg 3480 agatatttaa ttacaataac catttaaaaa accgtatata tcaatatgaa aaagagaaag 3540 cagaaacaga aaactcatga gagacaagca gtaagaaact tcttttggag aaacaacaga 3600 ccagatcttt actcacaact catgctagga ggccagtcct agcatcacct tatgttgaaa 3660 atcttaccaa tagtctgtgt caacagaata cttattttag aagaaaaatt catgatttct 3720 tcctgaagcc tacagacata aaataacagt gtgaagaatt acttgttcac gaattgcata 3780 aagctgcaca ggattcccat ctaccctgat gatgcagcag acatcattca atccaaccag 3840 aatctcgctc tgtcactcag gctgg 3865 16 3282 DNA Human 16 gggacagggc tgaggatgag gagaaccctg gggacccaga agaccgtgcc ttgcccggaa 60 gtcctgcctg taggcctgaa ggacttgccc taacagagcc tcaacaacta cctggtgatt 120 cctacttcag ccccttggtg tgagcagctt ctcaacatga actacagcct ccacttggcc 180 ttcgtgtgtc tgagtctctt cactgagagg atgtgcatcc aggggagtca gttcaacgtc 240 gaggtcggca gaagtgacaa gctttccctg cctggctttg agaacctcac agcaggatat 300 aacaaatttc tcaggcccaa ttttggtgga gaacccgtac agatagcgct gactctggac 360 attgcaagta tctctagcat ttcagagagt aacatggact acacagccac catatacctc 420 cgacagcgct ggatggacca gcggctggtg tttgaaggca acaagagctt cactctggat 480 gcccgcctcg tggagttcct ctgggtgcca gatacttaca ttgtggagtc caagaagtcc 540 ttcctccatg aagtcactgt gggaaacagg ctcatccgcc tcttctccaa tggcacggtc 600 ctgtatgccc tcagaatcac gacaactgtt gcatgtaaca tggatctgtc taaatacccc 660 atggacacac agacatgcaa gttgcagctg gaaagctggg gctatgatgg aaatgatgtg 720 gagttcacct ggctgagagg gaacgactct gtgcgtggac tggaacacct gcggcttgct 780 cagtacacca tagagcggta tttcacctta gtcaccagat cgcagcagga gacaggaaat 840 tacactagat tggtcttaca gtttgagctt cggaggaatg ttctgtattt cattttggaa 900 acctacgttc cttccacttt cctggtggtg ttgtcctggg tttcattttg gatctctctc 960 gattcagtcc ctgcaagaac ctgcattgga gtgacgaccg tgttatcaat gaccacactg 1020 atgatcgggt cccgcacttc tcttcccaac accaactgct tcatcaaggc catcgatgtg 1080 tacctgggga tctgctttag ctttgtgttt ggggccttgc tagaatatgc agttgctcac 1140 tacagttcct tacagcagat ggcagccaaa gataggggga caacaaagga agtagaagaa 1200 gtcagtatta ctaatatcat caacagctcc atctccagct ttaaacggaa gatcagcttt 1260 gccagcattg aaatttccag cgacaacgtt gactacagtg acttgacaat gaaaaccagc 1320 gacaagttca agtttgtctt ccgagaaaag atgggcagga ttgttgatta tttcacaatt 1380 caaaacccca gtaatgttga tcactattcc aaactactgt ttcctttgat ttttatgcta 1440 gccaatgtat tttactgggc atactacatg tatttttgag tcaatgttaa atttcttgca 1500 tgccataggt cttcaacagg acaagataat gatgtaaatg gtattttagg ccaagtgtgc 1560 acccacatcc aatggtgcta caagtgactg aaataatatt tgagtctttc tgctcaaaga 1620 atgaagctcc aaccattgtt ctaagctgtg tagaagtcct agcattatag gatcttgtaa 1680 tagaaacatc agtccattcc tctttcatct taatcaagga cattcccatg gagcccaaga 1740 ttacaaatgt actcagggct gtttattcgg tggctccctg gtttgcattt acctcatata 1800 aagaatggga aggagaccat tgggtaaccc tcaagtgtca gaagttgttt ctaaagtaac 1860 tatacatgtt ttttactaaa tctctgcagt gcttataaaa tacattgttg cctatttagg 1920 gagtaacatt ttctagtttt tgtttctggt taaaatgaaa tatgggctta tgtcaattca 1980 ttggaagtca atgcactaac tcaataccaa gatgagtttt taaataatga atattattta 2040 ataccacaac agaattatcc ccaatttcca ataagtccta tcattgaaaa ttcaaatata 2100 agtgaagaaa aaattagtag atcaacaatc taaacaaatc cctcggttct aagatacaat 2160 ggattcccca tactggaagg actctgaggc tttattcccc cactatgcat atcttatcat 2220 tttattatta tacacacatc catcctaaac tatactaaag cccttttccc atgcatggat 2280 ggaaatggaa gatttttttg taacttgttc tagaagtctt aatatgggct gttgccatga 2340 aggcttgcag aattgagtcc attttctagc tgcctttatt cacatagtga tggggtacta 2400 aaagtactgg gttgactcag agagtcgctg tcattctgtc attgctgcta ctctaacact 2460 gagcaacact ctcccagtgg cagatcccct gtatcattcc aagaggagca ttcatccctt 2520 tgctctaatg atcaggaatg atgcttatta gaaaacaaac tgcttgaccc aggaacaagt 2580 ggcttagctt aagtaaactt ggctttgctc agatccctga tccttccagc tggtctgctc 2640 tgagtggctt atcccgcatg agcaggagcg tgctggccct gagtactgaa ctttctgagt 2700 aacaatgaga cacgttacag aacctatgtt caggttgcgg gtgagctgcc ctctccaaat 2760 ccagccagag atgcacattc ctcggccagt ctcagccaac agtaccaaaa gtgatttttg 2820 agtgtgccag ggtaaaggct tccagttcag cctcagttat tttagacaat ctcgccatct 2880 ttaatttctt agcttcctgt tctaataaat gcacggcttt acctttcctg tcagaaataa 2940 accaaggctc taaaagatga tttcccttct gtaactccct agagccacag gttctcattc 3000 cttttcccat tatacttctc acaattcagt ttctatgagt ttgatcacct gattttttta 3060 acaaaatatt tctaacggga atgggtggga gtgctggtga aaagagatga aatgtggttg 3120 tatgagccaa tcatatttgt gattttttaa aaaaagttta aaaggaaata tctgttctga 3180 aaccccactt aagcattgtt tttatataaa aacaatgata aagatgtgaa ctgtgaaata 3240 aatataccat attagctacc caccaaaaaa aaaaaaaaaa aa 3282 17 503 DNA Human 17 gacagcggct tccttgatcc ttgccacccg cgactgaaca ccgacagcag cagcctcacc 60 atgaagttgc tgatggtcct catgctggcg gccctctccc agcactgcta cgcaggctct 120 ggctgcccct tattggagaa tgtgatttcc aagacaatca atccacaagt gtctaagact 180 gaatacaaag aacttcttca agagttcata gacgacaatg ccactacaaa tgccatagat 240 gaattgaagg aatgttttct taaccaaacg gatgaaactc tgagcaatgt tgaggtgttt 300 atgcaattaa tatatgacag cagtctttgt gatttatttt aactttctgc aagacctttg 360 gctcacagaa ctgcagggta tggtgagaaa ccaactacgg attgctgcaa accacacctt 420 ctctttctta tgtcttttta ctacaaacta caagacaatt gttgaaacct gctatacatg 480 tttattttaa taaattgatg gca 503 18 503 DNA Human 18 gacagcggct tccttgatcc ttgccacccg cgactgaaca ccgacagcag cagcctcacc 60 atgaagttgc tgatggtcct catgctggcg gccctctccc agcactgcta cgcaggctct 120 ggctgcccct tattggagaa tgtgatttcc aagacaatca atccacaagt gtctaagact 180 gaatacaaag aacttcttca agagttcata gacgacaatg ccactacaaa tgccatagat 240 gaattgaagg aatgttttct taaccaaacg gatgaaactc tgagcaatgt tgaggtgttt 300 atgcaattaa tatatgacag cagtctttgt gatttatttt aactttctgc aagacctttg 360 gctcacagaa ctgcagggta tggtgagaaa ccaactacgg attgctgcaa accacacctt 420 ctctttctta tgtcttttta ctacaaacta caagacaatt gttgaaacct gctatacatg 480 tttattttaa taaattgatg gca 503 19 1793 DNA Human 19 cgcgtccgcc ccgcgagcac agagcctcgc ctttgccgat ccgccgcccg tccacacccg 60 ccgccagctc accatggatg atgatatcgc cgcgctcgtc gtcgacaacg gctccggcat 120 gtgcaaggcc ggcttcgcgg gcgacgatgc cccccgggcc gtcttcccct ccatcgtggg 180 gcgccccagg caccagggcg tgatggtggg catgggtcag aaggattcct atgtgggcga 240 cgaggcccag agcaagagag gcatcctcac cctgaagtac cccatcgagc acggcatcgt 300 caccaactgg gacgacatgg agaaaatctg gcaccacacc ttctacaatg agctgcgtgt 360 ggctcccgag gagcaccccg tgctgctgac cgaggccccc ctgaacccca aggccaaccg 420 cgagaagatg acccagatca tgtttgagac cttcaacacc ccagccatgt acgttgctat 480 ccaggctgtg ctatccctgt acgcctctgg ccgtaccact ggcatcgtga tggactccgg 540 tgacggggtc acccacactg tgcccatcta cgaggggtat gccctccccc atgccatcct 600 gcgtctggac ctggctggcc gggacctgac tgactacctc atgaagatcc tcaccgagcg 660 cggctacagc ttcaccacca cggccgagcg ggaaatcgtg cgtgacatta aggagaagct 720 gtgctacgtc gccctggact tcgagcaaga gatggccacg gctgcttcca gctcctccct 780 ggagaagagc tacgagctgc ctgacggcca ggtcatcacc attggcaatg agcggttccg 840 ctgccctgag gcactcttcc agccttcctt cctgggcatg gagtcctgtg gcatccacga 900 aactaccttc aactccatca tgaagtgtga cgtggacatc cgcaaagacc tgtacgccaa 960 cacagtgctg tctggcggca ccaccatgta ccctggcatt gccgacagga tgcagaagga 1020 gatcactgcc ctggcaccca gcacaatgaa gatcaagatc attgctcctc ctgagcgcaa 1080 gtactccgtg tggatcggcg gctccatcct ggcctcgctg tccaccttcc agcagatgtg 1140 gatcagcaag caggagtatg acgagtccgg cccctccatc gtccaccgca aatgcttcta 1200 ggcggactat gacttagttg cgttacaccc tttcttgaca aaacctaact tgcgcagaaa 1260 acaagatgag attggcatgg ctttatttgt tttttttgtt ttgttttggt tttttttttt 1320 tttttggctt gactcaggat ttaaaaactg gaacggtgaa ggtgacagca gtcggttgga 1380 gcgagcatcc cccaaagttc acaatgtggc cgaggacttt gattgcacat tgttgttttt 1440 ttaatagtca ttccaaatat gagatgcatt gttacaggaa gtcccttgcc atcctaaaag 1500 ccaccccact tctctctaag gagaatggcc cagtcctctc ccaagtccac acaggggagg 1560 tgatagcatt gctttcgtgt aaattatgta atgcaaaatt tttttaatct tcgccttaat 1620 acttttttat tttgttttat tttgaatgat gagccttcgt gccccccctt cccccttttt 1680 gtcccccaac ttgagatgta tgaaggcttt tggtctccct gggagtgggt ggaggcagcc 1740 agggcttacc tgtacactga cttgagacca gttgaataaa agtgcacacc tta 1793 20 1377 DNA Human 20 cacacagcct actttccaag cggagccatg tctggtaacg gcaatgcggc tgcaacggcg 60 gaagaaaaca gcccaaagat gagagtgatt cgcgtgggta cccgcaagag ccagcttgct 120 cgcatacaga cggacagtgt ggtggcaaca ttgaaagcct cgtaccctgg cctgcagttt 180 gaaatcattg ctatgtccac cacaggggac aagattcttg atactgcact ctctaagatt 240 ggagagaaaa gcctgtttac caaggagctt gaacatgccc tggagaagaa tgaagtggac 300 ctggttgttc actccttgaa ggacctgccc actgtgcttc ctcctggctt caccatcgga 360 gccatctgca agcgggaaaa ccctcatgat gctgttgtct ttcacccaaa atttgttggg 420 aagaccctag aaaccctgcc agagaagagt gtggtgggaa ccagctccct gcgaagagca 480 gcccagctgc agagaaagtt cccgcatctg gagttcagga gtattcgggg aaacctcaac 540 acccggcttc ggaagctgga cgagcagcag gagttcagtg ccatcatcct agcaacagct 600 ggcctgcagc gcatgggctg gcacaaccgg gtggggcaga tcctgcaccc tgagaaatgc 660 atgtatgctg tgggccaggg ggccttgggc gtggaagtgc gagccaagga ccaggacatc 720 ttggatctgg tgggtgtgct gcacgatccc gagactctgc ttcgctgcat cgctgaaagg 780 gccttcctga ggcacctgga aggaggctgc agtgtgccag tagccgtgca tacagctatg 840 aaggatgggc aactgtacct gactggagga gtctggagtc tagacggctc agatagcata 900 caagagacca tgcaggctac catccatgtc cctgcccagc atgaagatgg ccctgaggat 960 gacccacagt tggtaggcat cactgctcgt aacattccac gagggcccca gttggctgcc 1020 cagaacttgg gcatcagcct ggccaacttg ttgctgagca aaggagccaa aaacatcctg 1080 gatgttgcac ggcagcttaa cgatgcccat taactggttt gtggggcaca gatgcctggg 1140 ttgctgctgt ccagtgccta catcccgggc ctcagtgccc cattctcact gctatctggg 1200 gagtgattac cccgggagac tgaactgcag ggttcaagcc ttccagggat ttgcctcacc 1260 ttggggcctt gatgactgcc ttgcctcctc agtatgtggg ggcttcatct ctttagagaa 1320 gtccaagcaa cagcctttga atgtaaccaa tcctactaat aaaccagttc tgaaggt 1377 21 1524 DNA Human 21 agcagacaga ggactctcat taaggaaggt gtcctgtgcc ctgaccctac aagatgccaa 60 gagaagatgc tcacttcatc tatggttacc ccaagaaggg gcacggccac tcttacacca 120 cggctgaaga ggccgctggg atcggcatcc tgacagtgat cctgggagtc ttactgctca 180 tcggctgttg gtattgtaga agacgaaatg gatacagagc cttgatggat aaaagtcttc 240 atgttggcac tcaatgtgcc ttaacaagaa gatgcccaca agaagggttt gatcatcggg 300 acagcaaagt gtctcttcaa gagaaaaact gtgaacctgt ggttcccaat gctccacctg 360 cttatgagaa actctctgca gaacagtcac caccacctta ttcaccttaa gagccagcga 420 gacacctgag acatgctgaa attatttctc tcacactttt gcttgaattt aatacagaca 480 tctaatgttc tcctttggaa tggtgtagga aaaatgcaag ccatctctaa taataagtca 540 gtgttaaaat tttagtaggt ccgctagcag tactaatcat gtgaggaaat gatgagaaat 600 attaaattgg gaaaactcca tcaataaatg ttgcaatgca tgatactatc tgtgccagag 660 gtaatgttag taaatccatg gtgttatttt ctgagagaca gaattcaagt gggtattctg 720 gggccatcca atttctcttt acttgaaatt tggctaataa caaactagtc aggttttcga 780 accttgaccg acatgaactg tacacagaat tgttccagta ctatggagtg ctcacaaagg 840 atacttttac aggttaagac aaagggttga ctggcctatt tatctgatca agaacatgtc 900 agcaatgtct ctttgtgctc taaaattcta ttatactaca ataatatatt gtaaagatcc 960 tatagctctt tttttttgag atggagtttc gcttttgttg cccaggctgg agtgcaatgg 1020 cgcgatcttg gctcaccata acctccgcct cccaggttca agcaattctc ctgccttagc 1080 ctcctgagta gctgggatta caggcgtgcg ccactatgcc tgactaattt tgtagtttta 1140 gtagagacgg ggtttctcca tgttggtcag gctggtctca aactcctgac ctcaggtgat 1200 ctgcccgcct cagcctccca aagtgctgga attacaggcg tgagccacca cgcctggctg 1260 gatcctatat cttaggtaag acatataacg cagtctaatt acatttcact tcaaggctca 1320 atgctattct aactaatgac aagtattttc tactaaacca gaaattggta gaaggattta 1380 aataagtaaa agctactatg tactgcctta gtgctgatgc ctgtgtactg ccttaaatgt 1440 acctatggca atttagctct cttgggttcc caaatccctc tcacaagaat gtgcagaaga 1500 aatcataaag gatcagagat tctg 1524 22 2384 DNA Human 22 tattgagttc ttcaaacatt gtagcctctt tatggtctct gagaaataac taccttaaac 60 ccataatctt taatacttcc taaactttct taataagaga agctctattc ctgacactac 120 ctctcatttg caaggtcaaa tcatcattag ttttgtagtc tattaactgg gtttgcttag 180 gtcaggcatt attattacta accttattgt taatattcta accataagaa ttaaactatt 240 aatggtgaat agagtttttc actttaacat aggcctatcc cactggtggg atacgagcca 300 attcgaaaga aaagtcagtc atgtgctttt cagaggatga aagcttaaga taaagactaa 360 aagtgtttga tgctggaggt gggagtggta ttatataggt ctcagccaag acatgtgata 420 atcactgtag tagtagctgg aaagagaaat ctgtgactcc aattagccag ttcctgcaga 480 ccttgtgagg actagaggaa gaatgctcct ggctgttttg tactgcctgc tgtggagttt 540 ccagacctcc gctggccatt tccctagagc ctgtgtctcc tctaagaacc tgatggagaa 600 ggaatgctgt ccaccgtgga gcggggacag gagtccctgt ggccagcttt caggcagagg 660 ttcctgtcag aatatccttc tgtccaatgc accacttggg cctcaatttc ccttcacagg 720 ggtggatgac cgggagtcgt ggccttccgt cttttataat aggacctgcc agtgctctgg 780 caacttcatg ggattcaact gtggaaactg caagtttggc ttttggggac caaactgcac 840 agagagacga ctcttggtga gaagaaacat cttcgatttg agtgccccag agaaggacaa 900 attttttgcc tacctcactt tagcaaagca taccatcagc tcagactatg tcatccccat 960 agggacctat ggccaaatga aaaatggatc aacacccatg tttaacgaca tcaatattta 1020 tgacctcttt gtctggatgc attattatgt gtcaatggat gcactgcttg ggggatctga 1080 aatctggaga gacattgatt ttgcccatga agcaccagct tttctgcctt ggcatagact 1140 cttcttgttg cggtgggaac aagaaatcca gaagctgaca ggagatgaaa acttcactat 1200 tccatattgg gactggcggg atgcagaaaa gtgtgacatt tgcacagatg agtacatggg 1260 aggtcagcac cccacaaatc ctaacttact cagcccagca tcattcttct cctcttggca 1320 gattgtctgt agccgattgg aggagtacaa cagccatcag tctttatgca atggaacgcc 1380 cgagggacct ttacggcgta atcctggaaa ccatgacaaa tccagaaccc caaggctccc 1440 ctcttcagct gatgtagaat tttgcctgag tttgacccaa tatgaatctg gttccatgga 1500 taaagctgcc aatttcagct ttagaaatac actggaagga tttgctagtc cacttactgg 1560 gatagcggat gcctctcaaa gcagcatgca caatgccttg cacatctata tgaatggaac 1620 aatgtcccag gtacagggat ctgccaacga tcctatcttc cttcttcacc atgcatttgt 1680 tgacagtatt tttgagcagt ggctccgaag gcaccgtcct cttcaagaag tttatccaga 1740 agccaatgca cccattggac ataaccggga atcctacatg gttcctttta taccactgta 1800 cagaaatggt gatttcttta tttcatccaa agatctgggc tatgactata gctatctaca 1860 agattcagac ccagactctt ttcaagacta cattaagtcc tatttggaac aagcgagtcg 1920 gatctggtca tggctccttg gggcggcgat ggtaggggcc gtcctcactg ccctgctggc 1980 agggcttgtg agcttgctgt gtcgtcacaa gagaaagcag cttcctgaag aaaagcagcc 2040 actcctcatg gagaaagagg attaccacag cttgtatcag agccatttat aaaaggctta 2100 ggcaatagag tagggccaaa aagcctgacc tcactctaac tcaaagtaat gtccaggttc 2160 ccagagaata tctgctggta tttttctgta aagaccattt gcaaaattgt aacctaatac 2220 aaagtgtagc cttcttccaa ctcaggtaga acacacctgt ctttgtcttg ctgttttcac 2280 tcagcccttt taacattttc ccctaagccc atatgtctaa ggaaaggatg ctatttggta 2340 atgaggaact gttatttgta tgtgaattaa agtgctctta tttt 2384 23 30 DNA Artificial Artificial sequence is a Probe 23 cctgaggcac ctggaaggag gctgcagtgt 30 24 27 DNA Artificial Artificial sequence is a Probe 24 atcaaaaaac aagcatggcc tcacacc 27 25 22 DNA Artificial Artificial sequence is a Primer 25 ctgcttcgct gcatcgctga aa 22 26 22 DNA Artificial Artificial sequence is a Primer 26 cagactcctc cagtcaggta ca 22 27 21 DNA Artificial Artificial sequence is a Primer 27 gcttggtggt taaaacttac c 21 28 20 DNA Artificial Artificial sequence is a Primer 28 tgaacagttc tgttggtgta 20 29 27 DNA Artificial Artificial sequence is a Probe 29 ctgcctgcct atgtgacgac aatccgg 27 30 20 DNA Artificial Artificial sequence is a Primer 30 caattttggt ggagaacccg 20 31 20 DNA Artificial Artificial sequence is a Primer 31 gctgtcggag gtatatggtg 20 32 28 DNA Artificial Artificial sequence is a Probe 32 catttcagag agtaacatgg actacaca 28 33 21 DNA Artificial Artificial sequence is a Primer 33 gcaagtgcca atgatcagag g 21 34 23 DNA Artificial Artificial sequence is a Primer 34 atatagactc aggtatacac act 23 35 27 DNA Artificial Artificial sequence is a Probe 35 tcccatcaga atccaaacaa gaggaag 27 

We claim:
 1. A method of extracting RNA from biological systems comprising contacting a solution containing RNA taken from the system with a substrate containing or to which is affixed a material binding to RNA and withdrawing the RNA by applying negative pressure wherein no centrifugation step exceeds 30 seconds.
 2. The method of claim 1 wherein the tissue is homogenized by means of a tissue grinder.
 3. The method of claim 1 wherein the biological system is a tissue and the viscosity of the solution containing RNA is reduced prior to contacting the solution with the substrate.
 4. The method of claim 1 wherein the negative pressure is from 11.6 to 13.1 psi.
 5. A method of extracting RNA from biological-systems comprising diluting an RNA homogenate and contacting a solution containing said diluted RNA homogenate with a substrate containing or to which is affixed a material binding to RNA and withdrawing the RNA by applying negative pressure.
 6. The method of claim 5 wherein said RNA homogenate is diluted to 8-2 mg of homogenate/diluent.
 7. The method of claim 5 wherein no centrifugation step exceeds 30 seconds.
 8. A method of extracting RNA from biological systems comprising removing from a sample of such systems, cells without RNA of interest, lysing cells containing RNA, contacting the lysate with a substrate containing or to which is affixed a material to which RNA can bind, applying negative in the absence of centrifugation, and removing RNA bound to the substrate; wherein said method is conducted in less than 6 minutes.
 9. The method of claim 8 wherein the cells are lysed with a substance containing guanidinium thiocyanate and the substrate is a siclia-gel membrane.
 10. The method of claim 8 further comprising the step of washing the lysate.
 11. The method of claim 8 further comprising the step of centrifuging the lysate before or after contact with the substrate.
 12. A method of extracting RNA from biological systems comprising: (a) obtaining a sample containing cells from the biological system, (b) removing from the sample, cells without RNA of interest to produce a working sample, (c) lysing the cells containing RNA that is of interest, (d) homogenizing the working sample, (e) wetting the homogenized working sample, (f) contacting the wetted, homogenized working sample with a substrate containing or to which is affixed a material to which RNA binds to form a substrate-RNA complex, (g) applying negative pressure to the substrate to extract the RNA, (h) washing the extracted RNA (i) removing water from the substrate-RNA complex, and (j) eluting the RNA wherein said method is conducted in less than 6 minutes.
 13. The method of claim 12 wherein cells without RNA of interest are lysed prior to removal.
 14. The method of claim 12 further comprising the step of diluting the homogenized working sample,
 15. The method of claim 14 wherein the working sample is diluted to between 8 and 2 mg of homogenate per ml of diluent.
 16. The method of claim 15 wherein the working sample is diluted to about 4 mg of homogenate to ml of diluent.
 17. The method of claim 14 wherein the diluent comprises a material that preserves RNA.
 18. The method of claim 17 wherein the material contains guanidinium thiocyanate
 19. The method of claim 12 further comprising centrifugation steps following steps g, h, i or j and wherein no such centrifugation step exceeds 30 seconds.
 20. The method of claim 12 wherein the substrate is a silica-gel membrane. 